The Federal Railroad Administration (FRA) requires periodic inspection of railways to ensure safety of track structures. The inspection requirements of railways are set forth in 49 CFR Part 213. In addition to other types of required inspections, such as the biannual inspection of tracks with ultrasonic and magnetic testers for internal defects, visual inspection of the tracks are required, as mandated by 49 CFR 213.233 (b):
Each inspection must be made on foot or by riding over the track in a vehicle at a speed that allows the person making the inspection to visually inspect the track structure for compliance with this part. However, mechanical, electrical and other track inspection devices may be used to supplement visual inspection. If a vehicle is used for visual inspection, the speed of the vehicle may not be more than 5 miles per hour when passing over track crossings, highway crossings, or switches.
The frequency of such visual inspection varies with the class of the track. Each track is classified depending on, for instance, the type of use to which the track is subjected, i.e., freight, hazardous freight, passenger, etc.; the speed for which the track is rated; the number and weight of the cars typically travelling over the track; etc. The most rigorous inspection schedule is twice weekly with at least a one calendar day interval between inspections. 49 CFR 213.233 (c). Because a number of different rail usages trigger the most rigorous inspection schedule, most of the main line railroad in the United States is required to comply with twice weekly visual inspections.
The types of anomalies to be detected by visual inspection are set forth in Part 213 of 49 CFR and generally encompass anything that effects the structure or the ability of trains to operate on the track. A competent inspector will note such things as loose spikes, defective ties, weeds or other growth growing near the tracks, brush or other growth blocking signals, blockage in a drainage ditch, catenary wires hanging too low, or a weakness in the ballast. Additionally, track inspectors sometimes find a crack in a rail, either by seeing the crack or, if the inspector is operating a vehicle, by hearing an unusual noise indicating a problem with the rail structure.
Currently, visual inspection of track is accomplished in one of two methods. In the first method, an individual inspector walks a length of track, viewing the track for anomalies. Upon detecting an anomaly, the inspector notes the type of anomaly and an approximate location of the anomaly, and either takes remedial action to correct the defect or orders an appropriate remedial action. Typically, a walking inspector covers 5 miles of track each day, at a rate of approximately 1.5 miles per hour. Because the FRA requires the track to be inspected twice per week, not on consecutive days, a standard inspection schedule for a walking inspector involves covering a five-mile segment of track on Monday, covering a second five-mile segment of track on Tuesday, repeating the first five-mile segment on Wednesday, repeating the second five-mile segment on Thursday, with Friday scheduled as a free day, enabling the inspector to inspect track that was missed during the week, for whatever reason, or to complete whatever paperwork is required. Thus, the walking inspector covers ten miles of track per week.
In the second method, a vehicle is used to travel a length of track, with one or more inspectors viewing the track through a window. The vehicle is generally a truck adapted to ride on rails, more commonly called a high rail truck. As in the first method, upon detection of an anomaly, the inspector notes the type of anomaly, an approximate location of the anomaly, and either takes remedial action or recommends an appropriate remedial action. An inspection vehicle typically travels at speeds of approximately 10 miles per hour, and thus covers approximately 50-60 miles of track per day. Inspection by vehicle follows an inspection schedule similar to that of a walking inspector, covering one segment of track on Monday, a second segment on Tuesday, repeating the two segments on Wednesday and Thursday, respectively, with Friday as a scheduled free day.
In general, the vast majority of visual inspections are performed using a high rail truck. Unfortunately, in areas where there is a high traffic incidence, it is not feasible to tie up the track with a high rail truck during the day, and nighttime testing with the vehicle is difficult due to lighting constraints. Hence, walking inspection is required in such areas. With either method, the cost of visual inspection of track is very significant. The assignee of the present invention, the National Railroad Passenger Corporation (hereinafter "Amtrak"), estimates that the costs of complying with the requirement for visual inspections of all tracks carrying passenger trains to account for approximately thirteen percent of the annual track maintenance expense incurred on the Northeast Corridor.
Attempts have been made to automate one or more of the inspections required by the FRA; however, none of the automated methods address the visual inspection requirements set forth in 49 CFR 213.233.
An example of an automated inspection system is a gauge restraint measuring system (GRMS), developed by the FRA in conjunction with the Association of American Railroads (AAR). The GRMS provides an indication of the relative lateral strength of the track structure. The system measures the lateral distance between the tracks, puts the track under a load, measures the loaded lateral distance between the track, calculates the incremental change between the unloaded and loaded lateral distance measurements, and utilizes the calculated incremental change to produce an indication of the relative lateral strength of the track structure, thus enabling the prediction of potential failure of the ties.
Yet another example of automated inspection is a vehicle developed by the assignee of the present invention, Amtrak, to collect and analyze track geometry and ride quality data for passenger track. The vehicle was developed responsive to the conditions imposed by the FRA responsive to a request by Amtrak for a waiver to operate passenger trains in excess of 110 mph. Under the conditions of the waiver, Amtrak is permitted to operate trains at speeds greater than 110 mph, provided a track geometry inspection car is operated on all affected track on a monthly basis. The vehicle is equipped with a track geometry measuring system (TGMS) which measures a number of geometrical components of the railroad track, such as the distance between the two rails (i.e., the track gage), the relative levelness of the rails to each other, the relative straightness of the two rails with respect to vertical and horizontal planes, and the shape of the curves of the track. The TGMS utilized by Amtrak is an inertial system, i.e., the system sets up an inertial reference frame to which the rail is compared. A measurement of track is taken approximately every foot, and differences exceeding a predetermined measurement are flagged, those differences affecting the safe and comfortable operation of the train over the track.
In addition to these automated inspection systems, pattern recognition systems are beginning to be utilized in railroad applications. One example is a rail profile measuring system, in which a video camera is utilized to view the rail and measure the shape of the rail. The images are returned to a computer to identify defects in or excessive wear of the rail. Additionally, the system employs a pattern recognition algorithm to compare the image of the rail to a preselected database of rail shape to identify the particular type of rail measured.
Unfortunately, none of these automated inspection vehicles fulfill the requirements of the FRA for visual inspection of track, set forth in 49 CFR 213.233; nor are they useful in reducing the costs associated with compliance with the visual inspection requirements.
Accordingly, it is one object of the invention to provide an improved inspection vehicle for visual inspection of railroad tracks.
Another object of the invention is to provide an improved inspection vehicle and method of inspection which reduce the high costs currently associated with visual inspection.
Yet another object of the invention is to provide an improved inspection vehicle and method of inspection which permits travel over railroad tracks at speeds in excess of 25 mph.
A further object of the invention is to provide an improved inspection vehicle and method of inspection providing a redundant/backup means for ascertaining defects.